Recently, technical development related to information processing devices worn on the head is being conducted. Such an information processing device is called a head-mounted display (HMD), for example, and includes a function of displaying images to a user wearing the HMD.
For example, Patent Literature 1 discloses a head-mounted image display device provided with an eyepiece lens and a light guide unit that guides emitted image light to a user's eye, which adjusts the emission angle of the emitted image light by moving the eyepiece lens or the light guide unit.
Additionally, HMDs generally are designed under the assumption that the HMD is attached in a predetermined direction. For example, the monocular HMD as disclosed in Patent Literature 1 is designed under the assumption that the HMD is attached either to the right or to the left of the user's head.